Search

Imha Reservoir has both a water transfer tunnel connecting Andong Reservoir and a selective withdrawal facility (SWF), which enable the innovative operation of the reservoir. Although these facilities had not been equipped when constructed in 1993, these structural measures were applied afterward as needed for the effective reservoir operation. The tunnel was constructed in 2015 to minimize the spillway discharge of a reservoir during floods by moving water to the other reservoir with free space. The SWF was installed in 2006 to address problems due to the persistent turbidity of Imha Reservoir. The effectiveness of these facilities was demonstrated through the operational cases in October 2019, while some improvements to non-structural measures were derived simultaneously. To prevent damage to the fish ecosystem of Imha reservoir, the tunnel currently was operated in a one-way water movement. However, a two-way water movement should be allowed as designed in the mid to long term. The SWF was operated effectively based on the prediction of the fate and transport of turbid water inside the reservoir using CE-QUAL-W2. Nevertheless, more action procedures on turbid water are required, such as setting clear criteria for the release timing of turbid water, predicting the downstream turbidity variations, etc.

In this study, the photocatalyst TiO2 was mixed with a general paint and applied on indoor walls as part of a mock-up test to measure the reduction in the NOx concentration affected by the on or off state of a UV lamp. The findings may be summarized as follows; the NOx concentration was reduced by approximately 7% more (0.134 ppm) with the UV lamp on than when the lamp was off in the indoor space where the paint mixed with TiO2 was applied.

This paper presents the control strategy of autonomous base station placement for localization of the GNSS interference source. The proposed algorithm deals with the optimization of the base station trajectory for target motion analysis based on bearing only tracking problem. The control strategy of the proposed algorithm is designed to maximize a cost function which is generally a functional of the Fisher information matrix. Compared to the optimal control methods, the proposed algorithm is easy to be designed and implemented, and constraints of multiple base stations’ trajectories can be effectively included. In addition, the proposed algorithm also considered target’s dynamics that is both uncertain and random, and there are multiple base stations for observing the target. In order to verify the performance of the proposed algorithm, simulation was performed with dynamic target case in the 2D scenario. It is assumed that the base stations’ networks have non-fully connected topology. According to the simulation results, it was confirmed that the proposed algorithm presents a flexible control strategy of autonomous multiple base stations’ placement for bearing only target tracking system.

Hydrocarbon leaks have a major accident potential and it could give significant damages to human, property and environment.To prevent these risks from the leak in design aspects, installation of ESD system is representative. Because the ESD system should be operated properly at any time, It needs high reliability and much cost. To make ESD system with high reliability and reasonable cost, it is a need to find specific design method.In this study, we proposed the multi-objective design optimization method and performed the optimization of the ESD system for 1st separation system to satisfy high reliability and cost-effective.‘NSGA-II (Non-dominated Sorting Genetic Algorithm-II)’ was applied and two objective functions of ‘Reliability’ and ‘Cost’ of system were defined. Six design variables were set to related variables for system configuration. To verify the result of the optimization, the results of existing design and optimum design were compared in aspects of reliability and cost. With the optimization method proposed from this study, it was possible to derive the reliable and economical design of the ESD system.

When the one-pass collection efficiency of each size of particles of the sound pressure machine equipped with a glass fiber HEPA filter to get rid of friable asbestos at the asbestos elimination field was evaluated, the collection efficiency of those with the size of 0.3um was examined to be 98.91%. That of the particles of 0.5um size was proved to be 99.21% on average, which is a little bit higher than that of 0.3um size. The 1.0um particles showed 100% of efficiency, and the collection efficiency of each size had statistically meaningful differences.

The causes of faults of induction motors are largely categorized into bearing fault, which causes a mechanical fault, and stator fault and rotor fault, which cause an electrical fault. A stator fault among these faults, which causes an electrical fault, occurs due to the breakdown of insulation, meaning the stator is directly connected with the power supply, and the direct connection is a direct cause of a major accident. For this reason, many studies are being performed to detect the faults. This paper explained the effects of a negative sequence on phase angle change by analyzing the effects of the existing negative sequence on the d-q transform of Park’s vector approach. This paper suggested a new algorithm that identifies the causes of stator faults with the use of the change in the duty ratio of the half-period frequency of the frequency when a phase angle change occurs at that moment.

Terminal velocity maximization of air-to-air agile missiles during agile turn phase is studied. It is important to make sure that agile missiles have enough velocity after agile turn stage in order to impact the target. The agile turn is operated during the boost phase. Thus, the agile turn problem is formulated as terminal velocity maximization with given final time. Optimal solutions are obtained by two different methods, pseudospectral method and parameterized costate optimization method. The parameterized costate optimization method is a part of shooting method of indirect method which is proposed to verify the solutions obtained by pseudospectral method. At first, the basic missile model with constant axial acceleration is treated in the two dimensional yaw plane. After looking into the basic missile model, missile model with aerodynamic forces and thrust is analyzed.

This paper describes the implementation of a 3D handheld scanning system based on visual inertial pose estimation and structured light technique.3D scanning system is composed of stereo camera, inertial navigation system (INS) and illumination projector to collect high resolution data for close range applications. The proposed algorithm for visual pose estimation is either based on feature matching or using accurate target object. The integration of INS enables the scanning system to provide the fast and reliable pose estimation supporting visual pose estimates. Block matching algorithm was used to render two view 3D reconstruction. For multiview 3D approach, rough registration and final alignment of point clouds using iterative closest point algorithm further improves the scanning accuracy. The proposed system is potentially advantageous for the generation of 3D models in bio-medical applications.

Image guided surgery using medical robots is becoming popular these days. For image guided surgery, a tracking system is required to provide 6DOF information of patient coordinate, surgical instruments and medical robots used in surgery. To provide 6DOF information, a marker has to be attached to the target. However, it is hard to use many markers all together because the markers will take too much space in the surgical area. The tracking system proposed in this study utilizes down sized markers compared to traditional markers by using micro-engraved data-coded pattern with a lens instead of using geometrically specified marker spheres as a tracking target. A tracking system is developed that has a measurement area of 1m to 2.5m from the tracking system. Experiment has been done for surgical navigation using the proposed tracking system and a medical robot.

Tracking system is essential for Image Guided Surgery(IGS). The Optical Tracking Sensor(OTS) has been widely used as tracking system for IGS due to its high accuracy and easy usage. However, OTS has a limit that tracking fails when occlusion of marker occurs. In this paper, sensor fusion with OTS and Inertial Measurement Unit(IMU) is proposed to solve this problem. The proposed algorithm improves the accuracy of tracking system by eliminating scattering error of the sensor and supplements the disadvantages of OTS and IMU through sensor fusion based on Kalman filter. Also, coordinate axis calibration method that improves the accuracy is introduced. The performed experiment verifies the effectualness of the proposed algorithm.